The present invention generally relates to communication right determination methods, information processing apparatuses and computer-readable recording mediums, and more particularly to a communication right determination method for determining a right to make a communication among a host computer and a plurality of terminal equipments, an information processing apparatus which uses the communication right determination method, and a computer-readable recording medium which is recorded with a program for carrying out the communication right determination method.
When making a data communication among a host computer and a plurality of terminal equipments, a communication adapter (hereinafter simply referred to as an adapter) is coupled to each terminal equipment, and the adapters are coupled by a cable while one adapter is selectively coupled to the host computer. The terminal equipment confirms from a signal line a connection state of the host computer and the other terminal equipments, and makes a communication in a state where the other terminal equipments are not making a communication.
According to the above described method, the adapter must be provided with a means for confirming and judging a state of the signal line. As a result, the cost of the adapter becomes high.
As another method of determining the right to make a communication, there is a method which adds identification (ID) numbers to the plurality of terminal equipments. The ID numbers are managed by the host computer, and a polling is successively made to the plurality of terminal equipments using the ID numbers, so as to determine the right to make a communication. However, according to this method, it takes time to make the communication because the polling must successively be made to the plurality of terminal equipments.
Therefore, there are demands to realize a communication right determination method which can be realized with ease at a low cost.
FIG. 1 is a diagram showing a first example of a conventional system. In this conventional system, a host computer 93 makers a data communication with a plurality of terminal equipments 91-1 through 91-N. A communication adapter 92 is provided with respect to each of the terminal equipments 91-1 through 91-N, and the host computer 93 and the terminal equipments 91-1 through 91-N are coupled by cables 94 in a daisy-chain.
When the terminal equipments 91-1 through 91-N communicate with the host computer 93, the adapter 92 detects the state of the signal on the cable 94, and makes a connection to the host computer 93 if there is no other terminal equipment in use.
On the other hand, the plurality of terminal equipments and the host computer can be coupled by assigning arbitrary ID numbers to each of the terminal equipments. In this case, the host computer can successively carry out a polling with respect to the terminal equipments using the ID numbers.
FIG. 2 is a diagram for explaining the operation of a second example of the conventional system which uses such ID numbers.
In a communication system shown in FIG. 2, a host computer 101 supplies a polling data to a terminal equipment 102-1 having an ID number xe2x80x9c001xe2x80x9d. If no request is generated in the terminal equipment 102-1 to make a communication with the host computer 101 when the polling data is supplied from the host computer 101, the terminal equipment 102-1 responds to the host computer 101 by returning a communication denial data as a response data.
The host computer 101 receives and analyzes the response data from the terminal equipment 102-1. If the analyzed response data is the communication denial data, the host computer 101 supplies the polling data to the terminal equipment having the next ID number, and the above described operation is repeated in a similar manner.
For example, if the response data from the terminal equipment 102-N is a communication acknowledge data, the host computer 101 communicates with the terminal equipment 102-N by carrying out a data communication process. During this time when the host computer 101 communicates with the terminal equipment 102-N, the polling data is not supplies to any of the terminals 102-1 through 102-N.
When the communication between the host computer 101 and the terminal 102-N ends, the host computer 101 again successively supplies the polling data to the terminal equipments 102-1 through 102-N starting from the terminal equipment 102-1 having the first ID number xe2x80x9c001xe2x80x9d, and operations similar to that described above are repeated.
However, according to the first example which detects the state of the signal line at the communication adapters coupled in the daisy-chain as shown in FIG. 1, confirms the communication state, and makes the communication only when no communication is made, it is necessary to provide in the communication adapters a hardware for detecting the state of the signal line. As a result, there is a problem in that the cost of the communication adapter, and thus, the communication system, increases.
On the other hand, according to the second example which assigns the arbitrary ID numbers to the terminal equipments and successively makes the polling with respect to the terminal equipments using the ID numbers as shown in FIG. 2, the ID number must be assigned to each of the terminal equipments, and the host computer must manage the ID numbers. Hence, there were problems in that the process becomes complex at both the terminal equipments and the host computer.
In addition, since the second example makes the polling from the host computer using the ID number with respect to each terminal equipment which is coupled to the host computer, there is another problem in that it takes time for the communications of all of the terminal equipments to end when a relatively large number of terminal equipments are coupled to the host computer.
Accordingly, it is a general object of the present invention is to provide a novel and useful communication right determination method, information processing apparatus and computer-readable recording medium, in which the problems described above are eliminated.
Another and more specific object of the present invention is to provide a communication right determination method, information processing apparatus and computer-readable recording medium which enable communications to be made at a low cost and within a relatively short communication time under an environment in which a plurality of terminal equipments are coupled to a host computer.
Still another object of the present invention is to provide a communication right determination method for determining a right to communicate between a host unit and a plurality of terminal equipments coupled to the host unit, comprising the steps of (a) transmitting polling information from the host unit simultaneously to the terminal equipments, (b) transmitting connection response information from the terminal equipments to the host unit at times which are different for each of the terminal equipments depending on the polling data received from the host unit, and (c) establishing a communication between the host unit and a predetermined terminal equipment from among the terminal equipments depending on the connection response information which is received from each of the terminal equipments. According to the communication right determination method of the present invention, it is possible to simultaneously transmit the polling information from the host unit to the terminal equipments using the same line, and the responses can be recognized independently at the host unit even when the responses are transmitted from the terminal equipments on the same line. As a result, the line can be simplified in that there is no need to couple the host unit and the terminal equipments using independent lines.
A further object of the present invention is to provide an information processing apparatus which communicates with a plurality off terminal equipments, comprising a polling information transmitting unit which transmits polling information simultaneously to the terminal equipments, and a communication establishing unit which establishes a communication between the information processing apparatus and a predetermined terminal equipment from among the terminal equipments depending on connection response information which is received from each of the terminal equipments in response to the polling information. According to the information processing apparatus of the present invention, the information processing apparatus, that is, a host unit, simply needs to simultaneously transmit the polling information to the terminal equipments when establishing the communication, without the need to transmit the polling information by distinguishing the terminal equipments. For this reason, it is unnecessary to manage the connection state and the like of the terminal equipments, and the information management at the host unit can be simplified.
Another object of the present invention is to provide an information processing apparatus which communicates with a host unit, comprising a connection response unit which transmits connection response information to the host unit at a time which is unique to the information processing apparatus in response to polling data received from the host unit, and a communication establishing unit which establishes a communication between the information processing apparatus and the host unit depending on a communication confirmation response which is received from the host unit in response to the connection response information. According to the information processing apparatus of the present invention, the connection response information transmitted from the information processing apparatus, that is, a terminal equipment, will not collide with connection response information transmitted from other terminal equipments which are coupled to the host unit. Hence, it is possible to share the connection between the host unit and a plurality of terminal equipments, thereby simplifying the connection between the plurality of terminal equipments and the host unit.
Still another object of the present invention is to provide a computer-readable recording medium recorded with a program for causing a computer to establish a communication with a plurality of terminal equipments, comprising polling information transmitting means for transmitting polling information simultaneously to the terminal equipments, and communication establishing means for establishing a communication between the computer and a predetermined terminal equipment from among the terminal equipments depending on connection response information which is received from each of the terminal equipments in response to the polling information. According to the computer-readable recording medium of the present invention, the computer, that is, the host unit, simply needs to simultaneously transmit the polling information to the terminal equipments when establishing the communication, without the need to transmit the polling information by distinguishing the terminal equipments. For this reason, it is unnecessary to manage the connection state and the like of the terminal equipments, and the information management at the host unit can be simplified.
A further object of the present invention is to provide a computer-readable recording medium recorded with a program for causing a computer to establish a communication with a host unit, comprising connection response means for transmitting connection response information to the host unit at a time which is unique to the computer in response to polling data received from the host unit, and communication establishing means for establishing a communication between the computer and the host unit depending on a communication confirmation response which is received from the host unit in response to the connection response information. According to the computer-redable recording medium of the present invention, the connection response information transmitted from the computer, that is, a terminal equipment, will not collide with connection response information transmitted from other terminal equipments which are coupled to the host unit. Hence, it is possible to share the connection between the host unit and a plurality of terminal equipments, thereby simplifying the connection between the plurality of terminal equipments and the host unit.
Another object of the present invention is to provide an information processing apparatus comprising a polling information transmitting unit which transmits polling information, and a communication establishing unit which establishes a communication with another information processing apparatus from which a response is received within a shortest time interval from a time when the polling information is transmitted from the polling information transmitting unit. According to the information processing apparatus of the present invention, the information processing apparatus simply needs to transmit the polling information when establishing the communication, without the need to transmit the polling information by distinguishing other information processing apparatuses. For this reason, it is unnecessary to manage the connection state and the like of the information processing apparatuses, and the information management at the information processing apparatus can be simplified.
Still another object of the present invention is to provide an information processing apparatus comprising a connection response unit which transmits connection response information in response to polling data received from another information processing apparatus, where the connection response unit transmits the connection response information after a time interval from a time when the polling data is received from the other information processing apparatus, and the time interval is uniquely set with respect to the information processing apparatus. According to the information processing apparatus of the present invention, the connection response information transmitted from the information processing apparatus will not collide with connection response information transmitted from other information processing apparatuses. Hence, it is possible to share the connection with other information processing apparatuses, thereby simplifying the connection between a plurality of information processing apparatuses.